The present invention relates to an ultrasound probe-driving transmitter driving an ultrasonic beam-emitting probe in an ultrasonic diagnostic system for obtaining diagnostic organic information by transmitting ultrasonic energy beamed into and reflected from an organism. More specifically, the invention relates to means for prohibiting the transmitter circuit assembly from driving the probe to emit ultrasonic energy which might otherwise be of excessive power in the event of malfunction in the transmitter.
Generally, ultrasonic diagnostic systems include a probe for emitting and detecting ultrasonic energy in waves beamed into and echoed from an organism, a transmitter circuit which generates pulses driving the probe, and a receiver circuit for processing the reflected ultrasonic echoes detected by the probe. The transmitter circuit includes a transmission control circuit for generating transmission interval and voltage information, a transmission trigger generation circuit for generating transmission triggers according to the transmission interval information, a transmission voltage generation circuit for generating transmission voltage corresponding to the transmission voltage information, and a drive pulse generation circuit for generating probe drive pulses. Furthermore, the transmitter circuit applies parameters Including pulse train number, beam focus depth or probe sectional drive area, transmission trigger interval and transmission voltage, to a drive pulse generation circuit, which generates drive pulses accordingly. Parameters such as pulse train number or beam focus depth are defined in software according to diagnostic mode.
In an ultrasonic diagnostic system as above, in a instance in which high-power ultrasonic waves are continually emitted in bursts into a patient organism under diagnosis, problems such as organic cavitation can occur. Therefore, care must be taken not to generate ultrasonic energy at power levels beyond diagnostic necessity. The power of the ultrasonic energy is related to emission burst frequency and ultrasound waveform factors, which are influenced by primary control parameters including voltage of pulses driving the probe, transmission trigger signal interval, probe sectional drive area (or aperture), beam focus depth and pulse train number. Thus, in conventional ultrasonic diagnostic systems, when parameter values set in the transmission control circuit by the software are applied to the pulse generation circuit, the parameter values are correspondingly set to limit the power of the ultrasonic energy waves.
In conventional systems, however, despite control of each parameter value, in the event of malfunction or aberration in the transmission voltage or the transmission trigger generation circuits, ultrasonic waves emitted at power levels injuriously beyond diagnostic necessity might be generated. For example, reduction of the transmission trigger interval due to abnormality in the transmission trigger generation circuit, or abnormal increase in the transmission voltage due to malfunction in the transmission voltage generation circuit, can result in the generation of excessive-power ultrasonic energy waves. In case there are aberrations in the software defining parametric values, moreover, excessive-power ultrasonic energy waves might be generated also.